package org.fisco.bcos.web3j.crypto.gm.sm2.util.encoders;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import org.fisco.bcos.web3j.crypto.gm.sm2.util.Strings;

/** Utility class for converting hex data to bytes and back again. */
public class Hex {
    private static final Encoder encoder = new HexEncoder();

    public static String toHexString(byte[] data) {
        return toHexString(data, 0, data.length);
    }

    public static String toHexString(byte[] data, int off, int length) {
        byte[] encoded = encode(data, off, length);
        return Strings.fromByteArray(encoded);
    }

    /**
     * encode the input data producing a Hex encoded byte array.
     *
     * @return a byte array containing the Hex encoded data.
     */
    public static byte[] encode(byte[] data) {
        return encode(data, 0, data.length);
    }

    /**
     * encode the input data producing a Hex encoded byte array.
     *
     * @return a byte array containing the Hex encoded data.
     */
    public static byte[] encode(byte[] data, int off, int length) {
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();

        try {
            encoder.encode(data, off, length, bOut);
        } catch (Exception e) {
            throw new EncoderException("exception encoding Hex string: " + e.getMessage(), e);
        }

        return bOut.toByteArray();
    }

    /**
     * Hex encode the byte data writing it to the given output stream.
     *
     * @return the number of bytes produced.
     */
    public static int encode(byte[] data, OutputStream out) throws IOException {
        return encoder.encode(data, 0, data.length, out);
    }

    /**
     * Hex encode the byte data writing it to the given output stream.
     *
     * @return the number of bytes produced.
     */
    public static int encode(byte[] data, int off, int length, OutputStream out)
            throws IOException {
        return encoder.encode(data, off, length, out);
    }

    /**
     * decode the Hex encoded input data. It is assumed the input data is valid.
     *
     * @return a byte array representing the decoded data.
     */
    public static byte[] decode(byte[] data) {
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();

        try {
            encoder.decode(data, 0, data.length, bOut);
        } catch (Exception e) {
            throw new DecoderException("exception decoding Hex data: " + e.getMessage(), e);
        }

        return bOut.toByteArray();
    }

    /**
     * decode the Hex encoded String data - whitespace will be ignored.
     *
     * @return a byte array representing the decoded data.
     */
    public static byte[] decode(String data) {
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();

        try {
            encoder.decode(data, bOut);
        } catch (Exception e) {
            throw new DecoderException("exception decoding Hex string: " + e.getMessage(), e);
        }

        return bOut.toByteArray();
    }

    /**
     * decode the Hex encoded String data writing it to the given output stream, whitespace
     * characters will be ignored.
     *
     * @return the number of bytes produced.
     */
    public static int decode(String data, OutputStream out) throws IOException {
        return encoder.decode(data, out);
    }
}
